1. Field of the Invention
Embodiments of the invention generally relate to a process kit for a semiconductor processing chamber, and a semiconductor processing chamber having a process kit. More specifically, the invention relates to a process kit that includes a ring and shield suitable for use in a physical vapor deposition chamber.
2. Description of the Related Art
Physical vapor deposition (PVD), or sputtering, is one of the most commonly used processes in the fabrication of electronic devices. PVD is a plasma process performed in a vacuum chamber where a negatively biased target is exposed to a plasma of an inert gas having relatively heavy atoms (e.g., argon (Ar)) or a gas mixture comprising such inert gas. Bombardment of the target by ions of the inert gas results in ejection of atoms of the target material. The ejected atoms accumulate as a deposited film on a substrate placed on a substrate support pedestal disposed within the chamber.
A process kit may be disposed in the chamber to help define a processing region in a desired region within the chamber with respect to the substrate. The process kit typically includes a cover ring, a deposition ring and a ground shield. Confining the plasma and the ejected atoms to the processing region helps maintain other components in the chamber free from deposited materials and promotes more efficient use of target materials, as a higher percentage of the ejected atoms are deposited on the substrate. The deposition ring additionally prevents deposition on the perimeter of the substrate support pedestal. The cover ring is generally used to create a labyrinth gap between the deposition ring and ground shield, thereby preventing deposition below the substrate. The cover ring also may be utilized to assist in controlling deposition at or below the substrate's edge.
Although conventional ring and shield designs have a robust processing history, the reduction in critical dimensions brings increasing attention to contamination sources within the chamber. As the rings and shield periodically contact each other as the substrate support pedestal raises and lowers between transfer and process positions, conventional designs are potential source of particulate contamination.
Moreover, since conventional cover ring designs are generally unconnected to temperature control sources, such as a chamber wall or substrate support pedestal, the temperature of the cover ring may fluctuate during the process cycle. The heating and cooling of the cover ring increases the stress in materials deposited on the cover ring, making the stressed material prone to flaking and particle generation. Thus, the inventors have realized that is would be advantageous to have a process kit that contributed to minimizing chamber contamination.
Therefore, there is a need in the art for an improved process kit.